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The average grain size of the as-received α-titanium is ASTM no. 4 [14].
Optical microscopy showed that the as received material had equiaxed grains with an average grain size of about 10μm (Figure 4).
Once the temperature falls below the transus temperature α nucleates at grain boundaries and then grows as lamellae into the (prior) β grains [24 ].
Buršák: Properties of Pure Titanium and Ultra Fine Grained Titanium, Metalurgija.
Patent Number 4390365, U.S.

This mainly due to the fact that there were more Mn and S elements in the substrate, and MnS-based inclusions formed inside the original austenite grains.
The grain refinement of phase transformation austenite to ferrite can be expressed by Eq. 11, the grain size of ferrite can be obtained by Eq.12 [8].
M=fαdγdα3 (11) dα=fαexpB0dγm-E/Ts1/3 (12) where Mis the average number of ferrite grains converted from each austenite grain,fα is the volume fraction of ferrite, dγ is the austenite grain size, dα is the ferrite grain size, Ts is the phase transition start temperature (K), E=5000 K-1, B0=49.6, m=0.036.
Inmedium carbon steel, the initial austenite grain size has a certain effect on the volume fraction of ferrite.
Grain refinement and strengthening of austenitic stainless steels during large strain cold rolling,J.

The simulation test results at 900 o C and 1000 o C revealed that STS 430J1L had a smaller number of sticking nucleation sites than the STS 436L.
The grain size of the STS 430J1L (133 µm) is finer than that of the STS 436L (174 µm).
This results might be associated with the finer grain size in the STS 430J1L.
Though the grain size of the STS 430J1L is somewhat smaller than that of the STS 436L, it can be expected that both microstructures are not much different because they basically consist of ferrite.
The STS 430J1L has a smaller number of sticking nucleation sites compared with the STS 436L, and leads to a smaller sticking amount in general.

The recrystallisation behaviour and the resulting grain structure after an O-temper annealing was checked by light microscopy.
At the higher temperature of 600°C the number of fine dispersoids is reduced.
Tab. 2 : Comparison process DC versus CC – Tensile testing results and grain size Table 2 shows the results of the tensile testing and the examination of the grain size after the O-temper annealing (Coil 350°C) at final thickness for both materials (DC and CC).
At a higher annealing temperature of 350°C (O-temper Coil 350°C) the CC-material is also recrystallized, but the grain size is very large (373 µm) and therefore the elongation value is reduced.
The DC-material shows a fine grain size (17 µm) and therefore higher elongation values than the CC-material.

With the position was close to the center, the grain size decreased.
Moreover, some grains with the size larger than 500 μm existed.
Most of the grains were dendritic shape and few grains were nearly spherical.
As a result, the number of nuclei is finite.
Gruzleski, Mechanism of grain refinement in aluminium, Acta Metall.

Gorana et al. [2] extensively demonstrated the influences of extrusion pressure, abrasive concentration and grain size on material removal, surface roughness, cutting forces and active grain density by means of AFM.
The experimental parameter levels designed with the Taguchi design of experiments not only reduces the number of experimental runs and saves costs but also identifies relative importance of each factor.
Impacts of four grain sizes on the polished surfaces under the same condition are shown in Figure 6.
Polishing with grain of still smaller size (4µm) generates almost worse surface, because when grain size gets very small, the viscosity of abrasive then increases to a point where less grains can be released out of the slurry for polishing.
When weight of PS is more than 80 grams, there will be too much pressure to the grains.

When the melt reachs the solid interior, initiates the grain boundary penetration causing grains to be detached and transfer to the melt.
Internal phases present in one type of ZrO2 grains.
Corroded and dissolved ZrO2 grains (insert) and Al2O3 grains (body) were observed.
However, the chemical attack and dissolution of ZrO2 grains (insert) and Al2O3 grains (body) were also present.
The ionic chemical bonding nature of the oxide systems help to understand the physical behaviour through the coordination number (CN).

For extruded ZK60 alloy, dynamic recrystallization grains (DRGs) change at a size range from 2 μm to 10 μm with average grain size of 5 μm.
Nucleation capacity of particles determines the start of solidification and number of effective nuclei at the solutal undercooling region.
Grain boundary is pinned and its sliding is inhibited effectively.
On the one hand, with decreasing the grain size, the impurity concentration on grain boundary decreases gradually and then the brittle fracture weakens.
Owing to the disorder atoms along grain boundary and different orientation among adjacent grains, the impediment of grain boundary is large when plastic deformation crosses from one grain to another grain.

The dark gray grain (Fig.
(b), point 1) was TiC particles, and the white grain (Fig.
It could be seen the irregular shape of TiC grain still existed, and the mean size of WC grains grew.
At the normal sintering temperature of TiC, the interaction between TiC and (W,Ti)C grains occurred, and the W atom in (W,Ti)C grains diffused and precipitated in the surface of TiC grains, which facilitated the formation of (W,Ti)C rim phase in the surface of TiC grains.
There was no large pieces of material falling off, only a small number of micro-pores appeared, indicating the wear resistance of alloy 5 was very excellent.

Therefore the abrasive grains of the new tool have more sharp edges than the grains of traditional abrasive tool.
During the processing, the sharp edges of the abrasive grains of the new tool intensify the metal cutting process.
The abrasive tool without a sheaf has a combination of large and small grains.
There are a large number of grains defects after the high temperature sintering.
The wear of this tool is caused by the cleaving of the grains.